Thermal printer and method of controlling the same

Abstract

Detecting a print density for the thermal paper based on the outputs of the first and second mark sensors, and adjusting print densities of the first and second thermal heads according to the detection results.

1. A thermal printer comprising:
 thermal paper, which has a thermosensitive layer on one side or both sides, and is fed in a predetermined direction; 
 a first thermal head which prints one side of the thermal paper; 
 a second thermal head which prints the other side of the thermal paper; 
 a control section which selectively prints one side and the other side of the thermal paper with the first and second thermal heads; 
 a first mark sensor which detects a mark printed on one side of the thermal paper; 
 a second mark sensor which detects a mark printed on the other side of the thermal paper; 
 a determination section which determines whether the thermal paper is double-side thermal paper printable on both sides or one-side thermal paper printable on only one side, according to the detection results of the first and second mark sensors; 
 a detection section which detects a print density for the thermal paper according to the outputs of the first and second mark sensors; and 
 an adjustment section which adjusts print densities of the first and second thermal heads, according to the detection results of the detection section. 
 
     
     
       2. The printer according to  claim 1 , wherein the first thermal head is positioned in the downstream of the second thermal head in the thermal paper feeding direction. 
     
     
       3. The printer according to  claim 1 , wherein the control section prints a mark on one side and the other side of the thermal paper with the first and second thermal heads, when the thermal paper is set,
 the determination section determines whether the thermal paper is double-side thermal paper printable on both sides or one-side thermal paper printable on only one side, according to the detection results of the first and second mark sensors, when the thermal paper is set, 
 the detection section detects a print density for the thermal paper according to the outputs of the first and second mark sensors, when the thermal paper is set, and 
 the adjustment section adjusts print densities of the first and second thermal heads, according to the detection results of the detection section, when the thermal paper is set. 
 
     
     
       4. The printer according to  claim 1 , wherein the determination section determines the thermal paper to be double-side thermal paper printable on both sides, when both first and second mark sensors detect marks,
 the determination section determines the thermal paper to be one-side thermal paper printable on only one side, when only the first mark sensor detects a mark, and 
 the determination section determines the thermal paper to be one-side thermal paper printable on only the other side, when only the second mark sensor detects a mark. 
 
     
     
       5. The printer according to  claim 1 , wherein the detection section detects a print density on the front side of the thermal paper according to the output of the first mark sensor, and detects a print density on the back side of the thermal paper according to the output of the second mark sensor, and
 the adjustment section adjusts a print density of the first thermal head according to the print density on the front side, out of the print densities detected by the detection section, and adjusts a print density of the second thermal head according to the print density on the back side. 
 
     
     
       6. The printer according to  claim 1 , further comprising a determination section which determines the thermal paper not to be thermal paper, when both first and second mark sensors do not detect marks. 
     
     
       7. A thermal printer comprising:
 thermal paper, which has a thermosensitive layer on one side or both sides, and is fed in a predetermined direction; 
 a first thermal head which prints one side of the thermal paper; 
 a second thermal head which prints the other side of the thermal paper; 
 control means for selectively printing one side and the other side of the thermal paper with the first and second thermal heads; 
 first mark sensing means for detecting a mark printed on one side of the thermal paper; 
 second mark sensing means for detecting a mark printed on the other side of the thermal paper; 
 determination means for determining whether the thermal paper is double-side thermal paper printable on both sides or one-side thermal paper printable on only one side, according to the detection results of the first and second mark sensing means; 
 detection means for detecting a print density for the thermal paper according to the outputs of the first and second mark sensing means; and 
 adjustment means for adjusting print densities of the first and second thermal heads, according to the detection results of the detection means. 
 
     
     
       8. The printer according to  claim 7 , wherein the first thermal head is positioned in the downstream of the second thermal head in the thermal paper feeding direction. 
     
     
       9. The printer according to  claim 7 , wherein the control means printing a mark on one side and the other side of the thermal paper with the first and second thermal heads, when the thermal paper is set,
 the determination means determining whether the thermal paper is double-side thermal paper printable on both sides or one-side thermal paper printable on only one side, according to the detection results of the first and second mark sensing means, when the thermal paper is set, 
 detection means detecting a print density for the thermal paper according to the outputs of the first and second mark sensing means, when the thermal paper is set, and 
 adjustment means adjusting print densities of the first and second thermal heads, according to the detection results of the detection means, when the thermal paper is set. 
 
     
     
       10. The printer according to  claim 7 , wherein the determination means determining the thermal paper to be double-side thermal paper printable on both sides, when both first and second mark sensing means detecting marks,
 the determination means for determining the thermal paper to be one-side thermal paper printable on only one side, when only the first mark sensing means detecting a mark, and 
 the determination means determining the thermal paper to be one-side thermal paper printable on only the other side, when only the second mark sensing means detecting a mark. 
 
     
     
       11. The printer according to  claim 7 , wherein the detection means detecting a print density on the front side of the thermal paper according to the output of the first mark sensing means, and detecting a print density on the back side of the thermal paper according to the output of the second mark sensing means, and
 the adjustment means adjusting a print density of the first thermal head according to the print density on the front side, out of the print densities detected by the detection means, and adjusting a print density of the second thermal head according to the print density on the back side. 
 
     
     
       12. The printer according to  claim 7 , further comprising determination means for determining the thermal paper not to be thermal paper, when both first and second mark sensing means do not detecting marks. 
     
     
       13. A method of controlling a thermal printer having:
 thermal paper, which has a thermosensitive layer on one side or both sides, and is fed in a predetermined direction; a first thermal head which prints one side of the thermal paper; a second thermal head which prints the other side of the thermal paper; a control section which selectively prints one side and the other side of the thermal paper with the first and second thermal heads; a first mark sensor which detects a mark printed on one side of the thermal paper; a second mark sensor which detects a mark printed on the other side of the thermal paper; and a determination section which determines whether the thermal paper is double-side thermal paper printable on both sides or one-side thermal paper printable on only one side, according to the detection results of the first and second mark sensors; 
 the method comprising: 
 detecting a print density for the thermal paper according to the outputs of the first and second mark sensors; and 
 adjusting print densities of the first and second thermal heads according to the detection results.